As a result, demand for diesel vehicles has soared as fleets and company car drivers seek tax savings and fuel efficiency benefits.

But, while diesel vehicles emit less CO2 than petrol models they are worse in terms of mono-nitrogen oxides (NO and NO2) and particulate matter, which are major air pollutants.

The European Union is already seeking to take legal action against the UK Government for its failure to meet air quality targets in a number of areas across the country, and London Mayor Boris Johnson is proposing to introduce the world’s first Ultra Low Emission Zone in the city in 2020.

Auction giant BCA’s newly published ‘Used Car Report 2014’, written by Professor Peter Cooke, of the Centre for Automotive Management, University of Buckingham Business School, called diesel emissions “a new cloud on the horizon”.

He writes in the report: “Given the popularity of diesel-engined cars particularly with fleet operators, sanctions against diesels may have implications for the used car market. Such sanctions may impact negatively on used diesel prices, while the focus may move to petrol-powered cars - with the possibility of higher used petrol car prices.”

latest tweets

Perform daily walk-around vehicle checks and report defects at the touch of a button with our award-winning MyVehic… https://t.co/8ETZmmHal1